1. Field of the Invention
The present invention pertains to warp sensing apparatus, and more particularly, to apparatus for determining the warp in disk-shaped articles such as drum lids and the like.
2. Description of the Art
Disk-shaped components are used in connection with production processes in many manufacturing applications. Such components may be subject to warping, which typically renders the components unacceptable for use. In the event warped components are used in a manufacturing process, quality problems result in the future use of the product being produced.
One of the applications where a warped component causes substantial quality problems is the production of storage drums, such as laminated fiber board drums. Prior to this time, drum manufacturers have had no easy way to determine whether the lids used in production were warped. Warped lids prevent the drum from sealing properly and can cause leakage or contamination of the material stored in the drum.
One of the most common means used to test for warped lids is by visual inspection and manual measurement. When the drums are being assembled and a worker believes that a lid is warped, the worker simply places the lid on a table or floor and measures the deviation from the horizontal plane by holding a ruler or other measuring instrument perpendicular to the table or floor. In many cases, the worker assembling the drums may not notice that the lids are slightly warped. In addition, an accurate measurement of the deviation or warp of the lid may not be possible because the shape of the lid makes it difficult to hold the lid and take a measurement at the same time.
Electro-mechanical transducers have been used for a number of years to convert basic mechanical dimensions, such as displacement, pressure, vibration, etc. into electrical signals. Transducers are used on a wide variety of equipment applications. None of the applications has provided a simple and cost effective means for determining whether a disk-shaped component is warped. Most manufacturers using disk-shaped components would find it desirable to have an inexpensive and efficient means for determining if the component is warped.